His psychotic smile became his signature expression to represent his insane nature without showcasing violence.
The character was created from Darkiplier, which is Markiplier's evil version that also has a psychopathic smile. He is way glitchier in nature than Stan in his future appearances.
The character of Stan was not fully developed in his older appearances as he had no name and he was canonly known as "Tristan's evil doppleganger".
Stan appeared in many videos in Soulz Studios. Some of them were short and some were large.
Sometimes Stan was red and recently he has the exact same colour skin as Tristan. He is actually the same in shape and form. At least, he seems like he is...